Most valuable parts of Africa?

New to the game. Generally speaking, what parts of Africa do you guys prioritize in the scramble? Or is it mostly a game of getting as much as you can rather than targeting specific parts?

As an aside, how much of an impact do African colonies even have economically. Is it actually worth going out of your way to get a piece, or is it more the principle of the matter? I'm Germany in my current game and I think the biggest impact might be the extra naval bases it let me build.